The invention relates to a height adjusting mechanism for an office chair, and more particularly, to a height adjusting mechanism which permits vertical adjustment of a back assembly of the chair.
Conventional office chairs have a seat assembly as well as a back assembly which extends upwardly from a rear edge of the seat assembly for respectively supporting the seat and back of the chair occupant. The seat assembly typically supports a rigid upright and the back assembly is supported on the upright. Also, such chairs often include a pair of chair arms which extend upwardly from the opposite side edges of the seat assembly for supporting the occupant""s arms.
To provide more comfortable office chairs, many of the chair components are adjustable in various directions so that the components of the chair more closely conform to and comfortably support the seat, arms and back of the occupant. In this regard, it is well known to provide a height adjusting mechanism in the back assembly of the chair which permits the height of the chair to be adjusted relative the to seat assembly. Height adjusting mechanisms also are known to be provided in the chair arms to permit vertical adjustment of the chair arm.
With respect to such height adjusting mechanisms and primarily those height adjusting mechanisms used in the back assembly, many of these mechanisms include ratchet-like mechanisms having a vertically elongate row of teeth, which define a rack, and a pawl which engages the rack. These ratchet mechanisms permit the back assembly to be manually lifted upwardly along the upright which mechanisms maintain the back assembly at a selected elevation when the occupant releases the back assembly.
Many of these mechanisms include actuator parts such as levers, pins and the like which act on the pawl when the back assembly is at the upper limit of vertical travel to separate the pawl from the rack and permit downward sliding, i.e. manual lowering of the back assembly to a lowered position. Such height adjusting mechanism includes further actuator parts at the lower end of travel which automatically disengage the lever, pins or the like to release or reset the pawl and permit the pawl to reengage the rack. With such height adjusting mechanisms, however, it is necessary to lower the back assembly to the lowermost position before the pawl is reset, i.e. is able to reengage the rack, and again permit upward adjustment of the height of the back assembly.
It is an object of the invention to provide an improved height adjusting mechanism which overcomes this and other disadvantages associated with prior height adjusting mechanisms.
The height adjusting mechanism of the invention is connected between a rigid upright extending upwardly from the seat assembly and an inner shell of the back assembly. The inventive height adjusting mechanism includes a lever-like latch which engages a vertically elongate rack to maintain the back assembly at a selected elevation, wherein the teeth of the rack define a plurality of incrementally spaced apart elevations. The latch is pivotable outwardly away from the teeth in a ratcheting manner to permit lifting of the back assembly upwardly to a selected one of the predefined elevations at which the latch engages the rack to maintain the back assembly at the selected elevation.
The latch further includes a release lever or cam which is pivotally connected to the catch so as to move therewith. The cam normally is in an inactive stored position which permits the latch to ratchet along the rack. However, the cam is pivoted at the upper end of travel of the back assembly toward the rack which causes the latch to move in an opposite direction away from the rack to a disengaged position which thereby allows lowering of the back assembly.
The release cam continuously contacts the inner shell of the back assembly during downward movement of the back assembly. However, due to frictional contact between the cam and a rack surface, the cam can be moved back to the stored position by a short upward shifting or reversal of the back assembly such that the latch reengages the rack. Accordingly, reengagement of the latch with the rack can be accomplished at any point between the upper and lower limits of travel of the back assembly. This thereby eliminates the need to drop the back assembly to the lower limit to reset the latch as is otherwise required in many known height adjusting mechanisms.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.